Individuals are often comfortable dealing with documents in hardcopy format. In general, hardcopy documents are easier to read, handle, and store than documents kept in the digital domain. However, control of document reproduction and dissemination is a concern because copies of documents containing sensitive information can be easily transmitted from person to person. As such, there is a risk of documents containing sensitive information being reproduced innocently or illicitly by persons without authorization.
Methods exist to limit the usefulness of unauthorized copying of documents. The emergence of electronic document processing systems has enhanced significantly the functional utility of plain paper and other types of hardcopy documents when the human readable information they normally convey is supplemented by writing appropriate machine readable digital data on them. This machine readable data enables the hardcopy document to actively interact with such a document processing system in a variety of different ways when the document is scanned into the system by an ordinary input scanner. Various methods of embedding machine readable code into documents in order to control the reproduction of documents have been tried, and are described in U.S. Pat. No. 4,728,984 entitled “Data Handling and Archiving System”, U.S. Pat. No. 5,982,956 entitled “Secure Method for Duplicating Sensitive Documents”, and U.S. Pat. No. 6,175,714 entitled “Document control system and method for digital copiers”, all of which are incorporated by reference in their entireties for the teachings therein.
Prior attempts to control reproduction offer access that is all or nothing. Once access is granted, it cannot be controlled in any other way. This makes it difficult to control who should have access to the information contained within the document. Prior attempts are limited in that typically an entire document contains machine readable code, and once access is granted, the entire document is decoded. Thus, there is a need in the art for a document to contain both human readable passages, and machine readable passages that encode sensitive information, where the decoding of the sensitive information is controlled by user authorization restrictions associated with the document.